A car is moving on a plane inclined at \( 30^\circ \) to the horizontal with an acceleration of \( 10 \, \text{m s}^{-2} \) parallel to the plane upward. A bob is suspended by a string from the roof of the car. The angle in degrees which the string makes with the vertical is ________.
(Take \( g = 10 \, \text{m s}^{-2} \) )
